New web component dropped: `<heading-anchors>`

Code: https://github.com/zachleat/heading-anchors
Blog: https://www.zachleat.com/web/heading-anchors/

Inspired by @DavidDarnes’s component of the same name and an excellent blog post by @ambrwlsn, this component adds and positions sibling anchor links for heading elements (h1–h6) when they have an `id` attribute.